Magnetic device



April 14,' 1959 WALENTINE ETAL MAGNETIC DEVICE 3 Sheets-Sheet 1.-

Filed July 2, 1956 INVENTORS. b L 71510127 lirmnwzx (lamp f Mar/011L110April 14, 1959- J. L'.WALENTINE ET AL MAGNETIC DEVICE 3 Sheets-Sheet 2Jam? 4 62 BY Filed July 2, 1956 United tates Patent MAGNETIC DEVICEJoseph L. Walenfine, Trenton, and Charles H. F. Morris, Jr., Allentown,N.J., assignors to Radio Corporation of America, a corporation ofDelaware Application July 2, 1956, Serial No. 595,326

17 Claims. (Cl. 340-174) This invention relates to magnetic devices, andmore particularly to magnetic devices useful in informationhandlingapplications.

The present invention is an improvement over that described in acopending application filed by Ian A Rajchman on September 13, 1954,Serial 455,724, entitled Magnetic Storage Device, and assigned to thesame assignee as the present invention.

In the aforesaid Rajchman application, there are described aperturedplates of magnetic material useful in information-handling applications.In certain embodiments of the Rajchman invention, the plates are formedof ferrite material and have a desired winding pattern thereoncomprising a conductive coating applied to both surfaces of the platesand the inside walls of the apertures. Various methods are suggested inthe Rajchman application for making the plates themselves and forobtaining the desired winding patterns by producing conductive coatingson the plates with the aid of masks.

It is desirable to make the apertured plates as thin as possible inorder to reduce the operating power required. It is found, however, thatthe thickness of the prior plates must be increased over a minimum valuerequired for mechanical strength to prevent warpage when the ferritematerial is sintered. One difliculty in using masks to obtain thedesired winding patterns is that the rate of shrinkage of the platesvaries from batch to batch during the sintering operation, and a new setof masks may be required for each batch of plates.

The primary object of our present invention is to provide an improvedapertured magnetic plate which is free from the aforementioneddifficulties.

' More particularly, it is an object of the present invention to providean improved apertured magnetic plate which, although quite thin,nevertheless is mechanically strong and is substantially free ofwarpage.

Another object of the present invention is to provide an improvedapertured magnetic plate adapted to have a conductive coating appliedthereon in a desired patter without requiring the use of masks.

Another object of the present invention is to provide an improvedmagnetic plate as aforesaid having a desired winding pattern thereonwhere the matrix from which the -desired winding pattern is obtained isan integral part of the plate itself.

Still another object of the present invention is to provide an improvedapertured magnetic plate as above set forth, and a method of fabricationthereof which results in a plate that is less expensive to manufacturethan plates heretofore known.

According to the present invention, apertured magnetic plates arefabricated by molding powdered ferrite material under pressure, using adie which provides a plurality of spaced ridges extending from both topand 'bottom surfaces of the plate, the ridges being integral with aportion of material between different ones of the apertures. The plateis then sintered in known fashion 2,882,519 Patented Apr. 14, 1959 toprovide the desired magnetic characteristics. The desired windingpattern is provided by first applying a conductive coating to all theexposed surfaces of the plate, including the aforesaid ridges and alsothe inside walls of the apertures, and then removing the coating fromthe ridges to provide the desired pattern.

In the accompanying drawing,

Fig. 1 is an isometric view of a portion of a magnetic device accordingto the present invention;

Fig. 2 is a top view of an apertured magnetic plate according to thepresent invention;

Fig. 3 is a bottom view of the plate of Fig. 2;

Fig. 4 is a cross-sectional view, somewhat enlarged, taken along theline 44 of Fig. 2; and

Fig. 5 is a cross-sectional view illustrating a suitable die and punchesfor making apertured plates according to the present invention.

In Fig. 1 there is shown a fragmentary portion of an apertured magneticplate 9 according to the invention. The plate 9 is comprised of amagnetic material having a substantially rectangular hystereischaracteristic and having a plurality of apertures 10 arrayed, forexample, in rows and columns. A suitable magnetic material ismanganese-magnesium ferrite.

Extending from the top surface of the plate 9 are longitudinal ridges12, each integral with the portion of the plate material between adifferent pair of columns of the apertures 10. Also extending from thetop surface of the plate 9 are transverse ridges 13. Each of thetransverse ridges 13 is integral with the portion of the plate materialbetween different, successive pairs of rows of the apertures 10.Extending from the bottom surface of the plate 9 is another series oflongitudinal ridges 15, each integral with the portion of the platematerial between a different pair of columns of apertures 10. Alsoextending from the bottom surface of the plate 9 is a plurality oftransverse ridges 17. Each transverse ridge 17 is integral with theportion of the plate material between difierent successive pairs of rowsof the apertures 10. The transverse ridges 17 on the bottom surface ofthe plate 9 alternate with the transverse ridges 13 on the top surfaceof the plate 9. Thus, each pair of rows of apertures 10 has one of thetransverse ridges 13 or 17 integral with the material between theirapertures 10. The locations of the transverse ridges 13 and 17,respectively extending from the top and the bottom surfaces of the plate9, are such as to provide a checkerboard winding arrangement, asdescribed more fully hereinafter. However, the transverse ridges 13 and17 may be integral with the portions of material on the top and bottomsurfaces, respectively, between each pair of rows of the apertures 10,if desired. The sides of each of the transverse and longitudinal ridgesare curved to provide easy withdrawal from the punches that are part ofthe means for forming the plates 9, as described hereinafter. Initially,each of the ridges may be bellshaped, for example. These transverse andlongitudinal ridges provide mechanical strength, serve to maintain theplate surfaces substantially parallel to each other during the sinteringoperation; and further provide the matrix from which the desired windingpattern is obtained.

A conductive metallic coating 20 is applied to all the exposed portionsof the plate 9, including the ridges 12, 13, 15 and 17 and the insidewalls of the apertures 10. The coating 20 may be removed subsequentlyfrom the top portions of the ridges by any suitable lapping or grindingoperation. The coating also is removed from the top and bottom edges ofthe plate 9. Electrical conductors are fastened to the coating 20 alongthe opposed side edges'of the plate 9, as by solder or cementing with aconductive paste, to provide leads for external connection to a suit bles gnal sou ce- Ih s i explained more fully with reference to Figs. 2 and3. The flat portion of plate material between the top and the bottom suces, and exc u ve of t e ridges, Provides the core material in whichflun is changed during operation. This flat portion has thickness dinthe order of a few thousandths ofan inch. Plates having a value .of ",dequal to 0.005" and having each of the ridges 0.005" thick, before thelapping or grinding operation, have been successfully manufactured.

The finished coating 20 on the top surface of an apertured plate,according to the present invention, is more clearly shown in Fig. 2. i i

Fig. 2 is a top viewlof an apertured plate 22 having, for example, eightrows and. eight columns of the apertures The transverse ridges 13 on thetop surface of the plate 22 divide' each column of thc'apertures' 19istofg r pa ts .b, .c, and each o a n a P o the pe ur s .10 The co ting29 i yc o th parts a, b, c, andd, on the top surface ofthe plate 2 2, pri c c n uous nnectiq be wecs h s in the .pair of apertures 10 of "eachof'the respective column parts a, b, c, and d. The longitudinal ridges12 extend between the top'and bottom edges of the plate 22 and separatethe various columns of the apertures 10 on the top surface of the plate22. Also the extreme left and right-hand columns are each separated fromthe sides of the plate 22 by a diflerent ridge 12.

The bottom view of the plate 22, shown in Fig. 3,

illustrates the manner in which the coating 20 forms a continuouselectrical connection to provide a series of separate linkages to thematerial about the separate apertures 10. The transverse ridges 17 onthe bottom surface of the plate 22 divide each column of the apertures10 into five parts, 1 w, x, y, and z. The column parts w, .r, and 3)each contain a pair of the apertures 10 and the other two column parts vand 2'. each contain only a single aperture it). The coating 2 in anyone of the column parts w, x, and y on the bottom surface of the plate22 provides a continuous connection between the coatings in the pair ofapertures of each of the respective column parts w, x, and y. Thelongitudinal ridges on the bottom surface of the plate 22 separate thevarious column-s of-the apertures 10. The ridges 15 extend from the topedge to the next-to-thelast transverse ridge 17 adjacent the bottom edgeof the plate 22. The ridges 15 extend from the bottom surface of theplate 22 to the next-to-the-last transverse ridge 17 adjacent the topedge of. the plate 22.

After the lapping or grinding operation, the transverse ridges 13"and 17(Figs. 2 and 3) are free of coating. threby' breaking the lconnection onboth the top and bottom surfaces of the plate '22 between adjacent andsuccessive pairs of the apertures 10.

The uppermost apertures 10 of the columnparts v of the adjacent columnson the bottom surface (Fig. 3) have a continuous coating to provide anelectrical connection successively between odd and even-numbered ones ofthe columns. The lowermost apertures 10 of the column parts 2. ofadjacent columns on the bottom surface have a continuous conductivecoating to provide an electrical connection successively between evenand odd-numbered ones of the columns. A conductor 24 is connected to theconductive coating of the lowermost column part z of the first orleft-hand column. (Fig. 3), and another conductor 26 is connected to theconductive coating 20 of the lowermost column part z of the last orright-hand column. The conductors 24 and 26 provide leads for connectionof the plate to a suitable signal source.

Fig. 4 illustrates more in detail the manner in which the" conductivecoating 20 links the apertures 10 of a column. Fig. 4 is a'cross-sectional view, somewhat enlarged, taken along the line 44 of Fig.2. Thus, be-

ginning at the bottom of the plate 22, the coating 20 l goes along thebottom surface of the plate 22, then through the lowermost aperture 10of the column and thence along the top surface of the plate 22, thenthrough the next aperture 10 of the column, and again along the bottomsurface of the plate, then through the next aperture 10 of the column,and then along the top surface of the plate, etc. Thus, between any twoof the apertures 10, the electrical coating is continuous only on onesurface, top or bottom, of the plate 22' and is broken on the othersurface due to the transverse ridges being staggered relative to eachother on opposite surfaces of the plate and the longitudinal sides beingaligned in pairs on the opposite surfaces. This arrangement constitutesa checkerboard winding arrangement wherein the direction of linkagebetween successive apertures 10 of a column successively reverses andwherein the direction of linkage between adjacent apertures 10 of twocolumns also reverses. If desired, the longitudinal ridges 12 and15'c'an be extended to theuppefand the lower edges of the plate 22 toprovide separate column windings. In such case, separate electricalconductors, not shown, are fastened to the separate top and bottomportions of the columns of the conductive coating. Also, if desired, theseparate transverse ridges 13 and 17 can be extended to the left and theright-hand edges of the plate 22 to provide separate row windings. insuch case. separate electrical conductors, not shown, are fastened tothe left-hand and right-hand portions of the separate rows of conductivecoating.

The electrical resistance of the coated winding may be reduced byplating copper over the silver coating. The copper plating operation maybe carried out before or after the lapping or grinding operation. If thecopper plating is carried out after the lapping or grinding operation,it can also serve as a visual check to assure that all the material hasbeen removed from the ridges.

A suitable mold for fabricating the apertured ridged plates of magneticmaterial is shown in cross-section in Fig. 5. The mold may be a part ofa hydraulic press and consists of a die 25, a top punch 27, a bottompunch 28, and a suitable number of core rods 30 fixed on a core rodholder 33. The top punch 27 has a suitable number of recesses 35 forreceiving the core rods 33 when the press is operated. A separate corerod 33 is provided for each separate aperture desired to be molded inthe finished plates. The faces of both the top and the bottom puncheshave depressions 37 machined therein, with each of the depressionscorresponding to the shape of a ridge to be provided in the moldedplate. The locations of the depressions 37 correspond to the locations.of the ridges of the molded plate. The magnetic material 39, which mayconsist, for example, ofa powdered man ganesefmagnesium ferritecomposition, is poured into the die cavity. The top punch 27 is thenmoved under pressure against the bottom punch 28 within the die 25, thetop and bottom punches 27 and 28 thereby forming the desired, ridged.apertured plate. Then the bottom punch 28 is moved upwardly within thedie 25 and the molded plate is removed.

What is claimed is:

'1. A magnetic core plane comprising a plate of sub stantiallyrectangular hysteresis loop material having regular geometrical arraysof aligned apertures, a plurality of spaced ridges for mechanicallystrengthening said plate, said ridges extending normally from oppositesurfaces of said plate, each of said ridges being integral with a.difierent portion of said material, said different portions eachincluding the material between difierent groups of said apertures, and awinding linking separate portions of the material about separate ones ofsaid apertures, the direction of linkage of said winding successivelyreversing in successive ones of said apertures, and said windingcomprising a conductive coating on said plate surfaces and on the insidewalls of said apertures.

2. A magnet c core p ane mpr sing a P at of, S b,-

stantially rectangular-hysteresis loop magnetic material having twoopposite surfaces and having apertures between said opposite surfacesarranged in rows and columns, a plurality of ridges for mechanicallystrengthening said plate, certain of said ridges being spacedlongitudinal ridges having sides and being integral with and extendingsubstantially normally from opposite surfaces of said plate, saidlongitudinal ridges on one surface being aligned with said longitudinalridges on the opposite surface, certain others of said ridges beingspaced transverse ridges having sides and being integral with andextending substantially normally from said opposite surfaces of saidplate, each of said transverse ridges on said one surface beingunopposed by a transverse ridge on said opposite surface, and a windingon said plate, said winding comprising a conductive coating on saidplate surfaces, on said ridge sides, and on the inside walls of saidapertures.

3. A magnetic core plane comprising a plate of substantially rectangularhysteresis loop magnetic material having two opposite surfaces andhaving apertures between said surfaces arranged in rows and columns, aplurality of longitudinal and transverse ridges for mechanicallystrengthening said plate and extending normally from both said surfaces,each of said longitudinal ridges being integral with a different portionof said material, each said different portion being located betweendifferent columns of apertures, each of said transverse ridges beingintegral with another different portion of said material, each otherdifferent portion being located between different rows of saidapertures, and windings on said plate, said windings comprisingconductive coatings on said plate surfaces and on the inside walls ofsaid apertures with certain of the surface coatings being seriallyconnected with the coatings of certain of said apertures.

4. A magnetic core plane comprising a plate of substantially rectangularhysteresis loop magnetic material having two opposite surfaces andhaving a plurality of apertures therein between said surfaces, aplurality of ridges for mechanically strengthening said plate, saidridges being integral with and extending normally from said platesurfaces in predetermined, spaced relation to said apertures, and awinding pattern linking said apertures, said winding pattern comprisinga conductive coating on said plate surfaces and on the inside walls ofsaid apertures, said ridges being spaced so as to break said conductivecoating at predetermined locations on said plate.

5. A magnetic core plane comprising a plate of substantially rectangularhysteresis loop magnetic material having apertures arrayed in rows andcolumns, a first plurality of transverse ridges extending substantiallynormally from one surface of said plate, each of said first tranverseridges being integral with the portion of material between differentpairs of rows of said apertures, a first plurality of longitudinalridges extending substantially normally from said one surface of saidplate, each of said first longitudinal ridges being integral with theportion of material between different columns of said apertures, asecond plurality of transverse ridges extending substantially normallyfrom the opposite surface of said plate, each of said last-namedtransverse ridges being integral with the portion of material betweenother different pairs of rows of said apertures, said first-nameddifferent pairs of rows and said other different pairs of rows eachincluding in common one row of said apertures, a second plurality oflongitudinal ridges extending substantially normally from said oppositesurface of said plate, certain of said last-named longitudinal ridgesextending between one edge of said plate and the next-to-the-last ofsaid second-named transverse ridges adjacent the opposite edge of saidplate and integral with the portion of material between successive pairsof said columns of apertures, and others of said last-named longitudinalridges extending between said opposite edge of said plate and thenext-to the-last of said second-named transverse ridges adjacent saidone edge of said plate and each integral with the portion of materialbetween different alternate, successive pairs of said columns ofapertures, and a conductive coating on said plate surfaces and theinside walls of said apertures, said coating forming a serial connectionbetween the coating portions in successive ones of said apertures in acolumn and between the coating portions of successive ones of saidcolumns of apertures.

6. A magnetic core plane comprising a plate of substantially rectangularhysteresis loop magnetic material having two opposite surfaces andhaving a plurality of apertures therein for receiving selectingwindings, each of said apertures extending from one to the other of saidsurfaces, and a plurality of ridges among said apertures formechanically'strengthening said plate, said ridges being integral withand extending normally from one of said plate surfaces.

7. A magnetic core plane comprising a plate of substantially rectangularhysteresis loop magnetic material having two opposite surfaces andhaving a plurality of apertures therein for receiving selectingwindings, each of said apertures extending from one to the other of saidsurfaces, a plurality of ridges among said apertures for mechanicallystrengthening said plate, certain of said ridges being integral with andextending normally from one of said surfaces, and others of said ridgesbeing integral with and extending normally from the other of saidsurfaces.

8. A magnetic core plane comprising a plate of substantially rectangularhysteresis loop magnetic material having two opposite surfaces andhaving a plurality of apertures therein for receiving selectingwindings, each of said apertures extending normally from one to theother of said surfaces, and a plurality of ridges among said aperturesfor mechanically strengthening said plate, said ridges being integralwith and extending normally from said plate surfaces, certain of saidridges on each of said plate surfaces intersecting certain of other ofsaid ridges on the same one of said surfaces.

9. A magnetic core plane comprising a plate of substantially rectangularhysteresis loop magnetic material having two opposite surfaces andhaving a plurality of apertures therein for receiving selectingwindings, each of said apertures extending normally from one to theother of said surfaces, and a plurality of ridges among said aperturesfor mechanically strengthening said plate, said ridges being integralwith and extending normally from said plate surfaces, at least certainof said ridges being staggered relative to each other on said oppositesurfaces.

10. A magnetic core plane comprising a plate of substantiallyrectangular hysteresis loop magnetic material having two oppositesurfaces and having a plurality of apertures therein for receivingselecting windings, each of said apertures extending from one to theother of said surfaces, and a plurality of ridges among said aperturesfor mechanically strengthening said plate, said ridges being integralwith and extending normally from said plate surfaces, at least certainof said ridges being aligned with each other in pairs on said oppositesurfaces.

11. A magnetic core plane comprising a plate of substantiallyrectangular hysteresis loop magnetic material having two oppositesurfaces and having a plurality of apertures therein for receivingselecting windings, each of said apertures extending from one to theother of said surfaces, and a plurality of ridges among said aperturesfor mechanically strengthening said plate, said ridges being integralwith and extending normally from said plate surfaces, certain of saidridges being aligned with each other in pairs on said opposite surfacesand certain others of said ridges being staggered relative to each otheron said opposite surfaces.

12. A magnetic core plane according to claim 11, wherein saidfirst-named certain ridges are angularly related to said second-namedcertain ridges.

13. A magnetic core plane comprising a plate of substantiallyrectangular hysteresis loop magnetic material having two oppositesurfaces and having regular geometrical arrays of aligned aperturestherein for receiving selecting windings, each of said aperturesextending from one to the other of said surfaces, a plurality of ridgesamong said apertures for mechanically strengthening said plate, each ofsaid ridges being integral with and extending normally from a differentportion of said plate surfaces, said difierent portions lying betweendifferent groups of one or more of said apertures.

14. A magnetic core plane comprising a plate of substantiallyrectangular hysteresis loop magnetic material having two oppositesurfaces and having a plurality of apertures therein arranged in rowsand columns for reciving selecting windings, each of said aperturesextending from one to the other of said surfaces, and a plurality oflongitudinal and transverse ridges for mechanically strengthening saidplate, said longitudinal ridges being integral with and extending nornially from said plate surfaces between difierent columns of saidapertures, and said transverse ridges being integral with and extendingnormally from said plate surfaces between different rows of saidapertures.

15. A magnetic core plane comprising a plate of substantiallyrectangular hysteresis loop magnetic material having surfaces includingtop and bottom surfaces and having a plurality of apertures therein,each of said apertures extending from one to the other of said top andbottom surfaces, a plurality of ridges among said apertures formechanically strengthening said plate, said ridges being integral withand extending normally from said top and bottom plate surfaces, and awinding separately linking the magnetic material about separte ones ofsaid apertures, said winding comprising a continuous conductive coatingon both of said plate surfaces and on the inside walls of saidapertures.

16. A magnetic core plane comprising a plate of sub.- stantiallyrectangular hysteresis loop magnetic material having surfaces includingtop and bottom surfaces and having a plurality of apertures therein,each of said apertures extending from one'to the other of said top andbottom surfaces, a plurality of ridges among said'apertures formechanically strengthening said plate, said ridges being integral withand extending normally from said top and bottom surfaces, and a windingseparately linking the magnetic material about separate ones of saidapertures, said winding comprising a continuous conductive coating onboth of said plate surfaces and on the inside walls of said apertures,and said ridges being at least partially devoid of said conductivecoating.

17. A magnetic core plane comprising a plate of substantiallyrectangular hysteresis loop magnetic material having two oppositesurfaces and having a plurality of apertures therein for receivingselecting windings, each of said apertures extending from one to theother of said surfaces, a plurality of ridges among said apertures formechanically strengtheningsaid plate, each of said ridges being integralwith and extending normally from a different portion of one of saidplate surfaces, said different portions lying between difierent groupsof one or more of said apertures.

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